Hitherto, in transmission of news material (data) of the broadcasting station, etc., because emergency is required, from a viewpoint such that adherence to high picture quality (mainly in the case of analog transmission; picture compression is used by the requirements based on the transmission band in the case of the digital transmission) is not particularly made, video materials photographed or image-picked up at the photographing field (site) are transmitted directly or after undergone editing, through channels of SNG (Satellite News Gathering). By employing such a transmission system, times required for delivery (transfer) of video materials of this kind are shortened, so improvement in the working efficiency has been made.
On the contrary, digital video materials such as (video) materials collected (gathered) in the drama, etc., which require high picture quality, require high transfer rate. In the case of production house, etc. which cannot ensure channels of SNG, as shown in FIG. 8, these digital video materials are recorded onto a magnetic tape to carry convey this magnetic tape to thereby carry out delivery (transfer) of video material.
Meanwhile, also in such production house, etc., if delivery of video materials can be made by using communication line, the time required for delivery is shortened accordingly. Thus, the working efficiency can be improved.
As one method thereof, a method in which B-ISDN which is one of public lines which can be easily utilized even in the production house of this kind is used to carry out transmission of video materials of this kind is conceivable.
However, the transmission system of the video material applied to (transmission equipment within) the production house, etc. is the synchronous transfer system in which video signals are caused to undergo transmission (transmitted) without break on real time basis, whereas in the case of the transmission system by B-ISDN, data are caused to undergo transmission (transmitted) by the asynchronous transfer mode for intermittently transmitting data with respective cells being as unit. There is great difference therebetween in respect of the above-mentioned point. Accordingly, in the case of the transmission system by B-ISDN, there was the problem that it is impossible to easily carry out transmission of video materials of this kind.
Further problem is that the fact that the transfer rate of video materials of this kind is greatly different from the transfer rate of B-ISDN also makes it difficult or impossible to easily carry out transmission of video materials of this kind.
This invention has been made in view of the above-mentioned problems, and its object is to provide a video signal transmission apparatus capable of transmitting/receiving video materials by the synchronous transfer system by using the transmission path by the asynchronous transfer mode.